Apparatus for stopping lost circulation



Oct. 8, 1957 p -rz 2,808,888

APPARATUS FOR STOPPING LOST CiRCULATION Filed Dec. 50. 1954 United States Patent 2,808,888 APPARATUS FOR STOPPING LOSTCIRCULATION Abraham J. Teplitz, Penn Township, Allegheny County, Pa., assignor to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware Application December 30, 1954, Serial No. 478,748

2 Claims. (Cl. 166-162) This invention relates to improved method and means for stopping lost circulation of drilling fluids and refers particularly to apparatus containing specifically adapted to stopping such lost circulation.

A major factor in the high cost of drilling many wells is the lost circulation of drilling fluids or mud into openings or thief zones in formations penetrated by the borehole; such lost circulation, in addition to involving loss of costly materials and expensive rig time can result in stuck drill pipes, a lost hole, blow-out, or'abandonment. When a condition of lost circulation once occurs, it is necessary, generally, to seal off" the thief zone before continuing the drilling operation. It has been the practice to introduce sealing material, usually a time-setting material such as cement, in the drilling fluid in the drill pipe and then pump it through the drill pipe and into the formation to plug the openings in the loss zone. In'this method, a large improvements.

volume of drilling mud must be lost in the course of being I displaced into the loss zone ahead of the sealing material, and there is, in addition, no assurance that the sealing material will-set, up in the openings to the loss zone and thus great quantities of sealing material can be lost also. If too much displacing fluid is used, the sealing material will be driven too far back in the loss zone to be efiective; if too little is used, the sealing material will not reach the zone. Furthermore, the sealing material may become diluted with drilling fluid in the course of being pumped to the loss zone and then fail to set up properly. An object of my invention is to provide means whereby sealing material can be delivered in concentrated form to the point of lost circulation without incurring additional loss of drilling fluid and can be fed to openings at a moderate pressure which will neither create more open ings in the loss zones nor force the sealing material back into the formation where it is unable to form an effective seal.

Briefly stated, my invention consists essentially of means for delivering a concentrated sealing material to a loss zone, the said means consisting essentially of a bailer, which bailer is closed at the bottom by a frangible disk to'which is aflixed a powdercap org'its equivalent that, upon exploding, will destroy the bottom closure of the bailer and allow the sealing material to flow out of the bailer into the surrounding periphery of the thief formation.

The bailer, which is supported on a cable for raising and lowering it in the borehole to a predeterminedpoint therein, can consist more specifically of an elongated, hollow, cylindrical housing of which at least the bottom end is closed, a frangible disk efiecting a destructible bottom closure, a mildly explosive cartridge or cap placed against the disk, a sleeve or threadedly attached assembly thereof for holding the disk against the housing, and wires connecting the cartridge to means operable from the ground surface for triggering the cartridge to destroy the disk. The bailer, or a part thereof,can be constructed of a drillable material such as a plastic, or a suitable metal 2,808,888 Fatented Oct. 8, 1957 ice or alloy, so that it will not be necessary to fish for and remove the bailer in case it becomes lodged in the borehole. The bailer is closed at the top and includes selfpropelling means for pressing sealing material into the openings. 7

In the accompanying drawings, which are supplied for the purpose of illustrating preferred embodiments of this invention, 1

Fig. l is a vertical sectional view of a bailer having a single means for destroying the frangible bottom-ofthe bailer and one arrangement for energizing this means, and I Fig. 2 is a vertical sectional view of an embodiment specifically adapted to providing self-generated means for delivering lost-circulation sealing material intoja loss formation.

Referring now to Fig. 1, the bailer shown therein con sists of an upper housing 10, which can be open at: the top 11, and a lower assembly 12, connected by screw threads to the upper housing and having a frangible-disk bottom 13.

The frangible disk 13 is held firmly between rubber gaskets 14 and by a sleeve 15 threadedly connected to .a cylindrical section 16 which in turn is connected tofthe upper housing 10. A bail or handle 17 is attached to the sleeve 15 for the purpose of grasping the lowerassembly 12, consisting of the sleeve 15 and cylindrical section 16, and screwing them to the upper housing 10. The; section 16, sleeve 15, and handle 17 areconstructed. of drillable materials. A blasting cap 18 is placed on thefrangible disk 13 in such position that when-it is exploded the frangible disk will be'sh atteredQ A thin drillable metal clip 19 is placed on the blasting cap 18, extends to the edges of the disk, and is held firmlyin place-betweenthe upper gasket 14 andthe bot t'omrir'n of cylindrical sec tion 16' Wires2tl and 20a lead from the blasting cap 18Ito'a bail or handle 21 having a con'nector 22; where the wires are conventionally connected into cable 23. Cable 23 constitutes the s'uspendingmeans by which the baileris lowered into a borehole. Alternatively-one of the wires 20 and 20a can be attached to hold-down. strip 19,-and be grounded through the strip'19 and .the cylindrical section 16, housing 10, bail 21, and suspending cabler23: a

The bailer can be filled with substantially any kind offree-lowing lost-circulation sealingmaterial and is especially suitable'for carrying large-sized. material which cannot be pumped into the borehole. When the bailer When a condition of lost circulation occurs and the introduction of drilling fluid into the borehole and its recirculation has been discontinued, the drilling fluidin the borehole will become balanced against the pressure in the thief zone and will stand at some level in the borehole. -When the bailer, which may be for example 40 to feet long, is introduced into the borehole it will displace part of the column of drilling fluid causing more fluid to flow into the loss formation. When the bailer has been placed near the point of loss and the frangible disk has been shattered, the sealing material then flows into .the openings in the thief zone. This occurs as a result of I reater than that or "the drilling fluid, or, otherwise, it I can be moved into the formation under the mild pressure off anadditional weight t drilling fluid added to thetop of thecolii'fnn of t 7 f Referring new more particularly to Fi 2 in which pai'ts the 'same as those in Fig.1 are indicated by the same reference characters, a spool piece 15 is screwed onto a lower cylindrical section 16 by the use of the bail or handle 17 whereby the frangible disk 13 is firmly held between the spool 15 and section '16 and against the gaskets 14. The frangible disk bears a blasting cap 18 held down by clip 19 and the cap 18 is connected to wires 20 and 2011 which trans nnthe current 'toexplode the cap. The upper section '24 of this bailer which is threadedly connected to lower section 16 is closed by a top 25; this top isfi'tte'd with aval'vf'ed inlet 26. The upper section 24 is'fsu bs'tantially-l'onger than the upper housing 10 of the bailer of Fig.1 in order top'rovide a gas space 27. The

- housing 24 is provided with a bail 28 and connector 29.

Beneath the bail 28 and resting on the top 25 is a housing 30 in whichc'an be placed a dry cell battery 31. A suspending cable :23 attached to the'c'onnector 29,,is em- 'ployed for lowering the bailer into a borehole. Mounted on the cable 23 at a point near the connector '29 are two separated contact points 32 and 33, the lower one of which is rigidly 'attached to the cable 23. The upper contact point 32 is 'slid'ably mountedconcentrically to the cable 23 and is vertically supported by a slight non-conductive spring 34 which separates it from contact point 33. The spring can fit into convex "sections 32a and 33a so that when the spring34 is compressed, points 32 and 33 will make contact with each other.

A 'go-'de'v'i1 '35 can be 'slipped'on the cable 23 at the surface an'd will slide down; the cable and strike 'slidabl'e point 32. This will close the circuit which consists of.

wire 36 leadin from battery 31 to contact point '33 and wire '20 leading fromfcont'ac't'point '32 to the blasting cap 1 8. d leads from the battery 31 to the blasting cap 18. Y I

In employing the better of Fig. 2, the holidown cli wires, and blasting cap are first put in place and spool 15 is screwed onto section 16 to hold the frangible disk 13 in position. The wires 20 and 20a are strung through the "section '24. I The bailer then partially filled with a sealing material, this being most conveniently accomplished by lowering the baile 'r into the borehole and holding it therein with slips at alevel such that'the top of the bailer can be reached for filling. After the bailer is partially filled with sealing material, the top '25 is screwed into position and the 'ivvires are connected tothe cable 23.

A gas, e. g., carbon dioxide or nitrogen, is pumped into the bailer' through thevalved inlet 26 until a mild pressure of gas is established within the bailer. This gas pressure, after the disk 13 is destroyed, will provide a mild driving force' t'o gently push the sealing material 11701111116 bailer irito the loss zone. This embodiment is especially useful when the sealing material is of lower specific gravity than the-drilling fluid.

Several modifications, in addition to those shown in Figs. 1 and 2, of means for shattering the frangible disk 13 can be employed. A go' devil can be caused to trigger a cocked spring attached to a pointed rod which, when the spring is released, will penetrate and shatter the frangible disk. Other means can include thermal shock or melting, such as would be-accomplished by energizing a heating coil placed in a disk of low melting point.

some of the se'aling'materials that can be used in the bailer of my invention includecement, comminuated nut shells, cottonseed huts, and fibrous materials. Hydra'table sealing materials such as bentonite can also be employed,

the latter preferably in admixturewith' a lubricant. In addition to the advantage otavoidingdiluti on of the sealing material, my methodand. means'ior sealing loss formations also has the advantage that particles of larger size than that of particles which can pass through pumps or the ports in the drill bit can easily be employed.

Having described my invention, 1 claim:

'l. Apparatus for clel'iveringa fiowab'le material to a predetermined point in a' borehole of a well comprising a hollow cylindrical housing, a frangible disk closing the lower 'endo'f the housing, an explosive charge adjacent the frangible disk adapted to rupture the'disk upon detonation, means'operable from the well head for detonating the explosive charge, a gas tight 'top closing the upper end of the housing, flowable materialin the lower portion of the housingacompressed gas within thehousing above the flowable material and adapted to force the fiowable material from the housing on rupture of the disk, and a supporting cable connected to the housing and extending to the -well head for suspending the housing at the desired height in the well. 7

2. Apparatus as set forth in claim 1 in which a' valved inlet opens'ii to the housing for introduction of the compresseti'gas into the housing.

'' ReterencesCiteil'in the 'file of this patent 1 STATES PATENTS.

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2,669,880 Dyer Sept. 9,1952

2,619,180 Smiihet a1. Nov. 25, 1952 2,623,595 7 West Dec. 30, 1952 

